Rishi Khatau weighed seven stone and was only four year’s old when doctors performed a gastric bypass and cut away nearly three-quarters of his stomach.

The young boy was born weighing just 3lb 9oz but rapidly began to gain weight and was diagnosed with Prader-Willi Syndrome – which means his body cannot burn calories properly and so hie weight continues to increase constantly.

Mr Khatu,39, said: “After the op, we saw a change in his sleep almost immediately. It makes me very happy that my son is getting his life back.

“He still has a craving for sweets, so we make him share his food, that way he’s having what he wants but only half the actual portion.”

Weight-loss surgery on children is considered only in rare and life-threatening cases.